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John T Philbrick

Publications and source records attributed to John T Philbrick.

13 recordsLinked to original sources
PubMed2006

Uptake rates for breast cancer genetic testing: a systematic review.

PURPOSE: Individuals and families dealing with the possibility of hereditary cancer risk face numerous decisions, including whether to obtain genetic testing. The purpose of this article is to determine what is known about the rate at which people obtain cancer genetic testing. METHODS: Using MEDLINE, CINAHL, and PSYCHINFO plus reviewing reference lists of relevant articles, we identified 40 studies in May 2002 that addressed breast cancer-related decisions, enrolled adult participants, were published in 1990 or more recently, were peer-reviewed primary clinical studies, addressed genetic testing either alone or in combination with genetic counseling, and reported rates at which participants showed interest in and/or underwent cancer genetic testing. Information regarding study design, participants, and genetic testing uptake rates was recorded. Each article was reviewed for methodologic quality using a flexible quality review system applicable to all study types. RESULTS: Of the 40 studies, 25 provided information about hypothetical genetic testing decisions, 14 about real decisions, and 1 about both. Mean hypothetical uptake was 66% (range, 20-96%) and real uptake was 59% (range, 25-96%). Multivariate logistic regression analyses found that decision type (real/hypothetical), personal and family history of breast cancer, and variability in sampling strategy, recruitment setting, and criteria for real and hypothetical uptake were independently associated with uptake. Our systematic review identified additional explanations for uptake variability (investigator influences, small sample sizes, variability in target populations, lack of clearly described sampling strategies, sampling methods open to bias, and variability in reporting associated risk factors). CONCLUSION: In addition to clinical characteristics, research methodologic issues are likely to be major determinants of variability in published breast cancer genetic testing uptake rates. An understanding of these issues will clarify to clinicians why their clinical experience may not be congruent with published rates and help guide future research.

Adult↗
PubMed2005

Free clinics: a national survey.

OBJECTIVES: To describe the scope and value of services provided by free clinics across the United States. METHODS: Mail survey of directors of free clinics registered in the Free Clinic Directory of the Free Clinic Foundation of America, November 2001, concerning the calendar year 2001. RESULTS: Eighty two percent (281/355) of clinics responded. Seventy five percent of clinics described their target population as the "uninsured" and 23% as "low income". Fifty five percent had income based eligibility criteria of 200% Federal poverty level or less. Clinics provided a mean of 5,989 patient visits/year and 11,202 prescriptions/year to 2,311 unique patients. 61.8% of patients were female, 80.4% between ages 19 to 64, 55.1% white, 21.8% black, and 18.7% Hispanic. Clinics were open 29.7 hours/week, 4.1 days/week, and 32.9% had a licensed pharmacy. The mean annual budget was $458,028 and clinics were staffed by 156.7 volunteers and 6.9 paid employees per clinic. CONCLUSIONS: Free clinics have become an established part of the safety net for the uninsured. The differences among the clinics are striking, supporting the conclusion that a variety of approaches to the care of the underserved can be used. However, despite their efforts, the responding free clinics manage to provide care to only 650,000 of the nation's 41 million uninsured.

Adolescent↗
PubMed2004

D-dimer testing for deep venous thrombosis: a metaanalysis.

BACKGROUND: The use of D-dimer assays as a rule-out test for deep venous thrombosis (DVT) is controversial. To clarify this issue we performed a systematic review of the relevant literature. METHODS: We identified eligible studies, using MEDLINE entries from February 1995 through October 2003, supplemented by a review of bibliographies of relevant articles. Studies reporting accuracy evaluations comparing D-dimer test results with lower extremity ultrasound or venography in symptomatic patients with suspected acute DVT were selected for review. Two reviewers critically appraised each study independently according to previously established methodologic standards for diagnostic test research. Those studies judged to be of highest quality were designated Level 1. RESULTS: The 23 Level 1 studies reported data on 21 different D-dimer assays. There was wide variation in assay sensitivity, specificity, and negative predictive values, and major differences in methodology of reviewed studies. A multivariate analysis of assay performance, controlling for sample size, DVT prevalence, reference standard, and patient mix, found few differences among the assays in effect on test performance as measured by diagnostic odds ratio. Increasing prevalence of DVT was associated with poorer test performance (P = 0.01), whereas the choice of venography as the reference standard was associated with better test performance (P <0.005). CONCLUSIONS: Explanations for the wide variation in assay performance include differences in biochemical and technical characteristics of the assays, heterogeneity and small size of patient groups, and bias introduced by choice of reference standards. Assay sensitivity and negative predictive value were frequently <90%, uncharacteristic of a good rule-out test. General use of D-dimer assays as a stand-alone test for the diagnosis of DVT is not supported by the literature.

Biomarkers↗
PubMed2004

Repeated-measures modeling improved comparison of diagnostic tests in meta-analysis of dependent studies.

OBJECTIVE: Current methods for meta-analysis of diagnostic tests do not allow utilizing all the information from papers in which several tests have been studied on the same patient sample. We demonstrate how to combine several studies of diagnostic tests, where each study reports on more than one test and some tests (but not necessarily all of them) are shared with other papers selected for the meta-analysis. We adopt statistical methodology for repeated measurements for the purpose of meta-analysis of diagnostic tests. STUDY DESIGN AND SETTING: The method allows for missing values of some tests for some papers, takes into account different sample sizes of papers, adjusts for background and confounding factors including test-specific covariates and paper-specific covariates, and accounts for correlations of the repeated measurements within each paper. It does not need individual-level data, although it can be modified to use them, and uses the two-by-two table of test results vs. gold standard. RESULTS: The results are translated from diagnostic odds ratios (DOR) to more clinically useful measures such as predictive values, post-test probabilities, and likelihood ratios. Models to capture between-study variation are introduced. The fit and influence of specific studies on the regression can be evaluated. Furthermore, model-based tests for homogeneity of DORs across papers are presented. CONCLUSION: The use of this new method is illustrated using a recent meta-analysis of the D-dimer test for the diagnosis of deep venous thrombosis.

Biomarkers↗
PubMed2003

The d-dimer test for deep venous thrombosis: gold standards and bias in negative predictive value.

BACKGROUND: Because venous ultrasound (US) fails to fully image the calf veins, there is the potential for US gold standard studies to classify patients with calf deep venous thrombosis (DVT) in the nondiseased category, causing bias in test index calculations. A false increase in negative predictive value (NPV) is especially likely because calf DVT false-negative tests will be counted in the numerator along with the true-negative tests in NPV calculations. We verified the presence and magnitude of this bias for the d-dimer test. METHODS: We abstracted data on overall (calf and thigh) and thigh-only test sensitivity, specificity, and NPV from the six English language studies published between March 1995 and October 2001 that compared d-dimer to a gold standard (GS) capable of imaging both thigh and calf veins and that also stratified results by thigh and calf location. Thigh specificity and NPV were calculated classifying calf DVT patients as free of disease. RESULTS: The six studies included 81-214 participants and provided 26 comparisons of 16 different d-dimer assays to the GS. Thigh sensitivity was higher than overall sensitivity in 22 of 26 comparisons (range, -0.3 to 8.6); thigh specificity was lower than overall specificity in all comparisons (range, -0.7 to -7.8); and thigh NPV was higher than overall NPV in 22 of 26 comparisons and unchanged in 4 comparisons (range, 0.0-9.2). NPV was >95% in 20 of the thigh results but >95% in only 8 of the overall results. CONCLUSIONS: Different GS can produce clinically significant differences in test indices. Care must be taken in interpreting DVT studies that evaluate d-dimer as a rule-out test and that use US as a GS, because missed calf DVT can falsely increase the NPV.

Bias↗